Manufacture of artificial silk from viscose



Patented Oct. 25, 1927 UNITED STAT .Arsr OFFICE. 1

WILLIAM MENDEL, OF BEVERLY, NEW JERSEY, ASSIGNOR TO SAMUEL A. NEIDICH, OF EDGEWATER PARK, NEW JERSEY.

MANUFACTURE OF ARTIFICIAL SILK FROM VI SCOSE.

No Drawing.

My invention relates to the manufacture jected to subsequent cleaning processes and.

thereafter dried to form the commercial artificial sllk.

Natural silk filaments have an average 'di-' ameter of .015 millimeter and, therefore, it

is highly desirable to produce artificial silk filaments of approximately the same diameter. However, the aforesaid coagulated viscose elements must, of course, be of sufficient strength to withstand the stresses of manipulation incident to their production, and as the viscose products of ordinary processes are muchweaker and more frangible than the natural silk filaments; it "has been found impossible tocommercially manufacture viscose silk filaments which are less than double the diameter of the natural silk filaments. For instance, if dried in air, the minimum diameter of ordinary viscose silk filaments is .03051 millimeter and if'viscose silk filaments are subjected to the action of glycerine, as is usual to' improve their flexibility, the minimum ultimate diameter attainable is .03545 -millimeter.

' Therefore, an object and effect of my invention is to provide a method and means for commercially producing viscose silk filalow cost, strong acid baths, such as aqueous solutions containing eight per cent" of S111 phuric acid or five per cent of hydrochloric acid, are v commonly used. With baths of that character, substantially all of the sulphur rimarily chemically combined with the cel ulose in viscose is released as free sulhur, but is occluded in the mass of cellulose iiydrate, causing the latter to present an undesirable dull yellow white appearance, whereas, natural silk has a char cteristic lustrous, translucent appearance. T erefore, such ordinary processes of coagulation must be supplemented by successive treatments of the coagulated viscose in chemical baths with a view t removal of the sulphur impurities a pitted surface.

ments as fine, lustrous and elastic as natural 7 Application filed May 23, 1925. Serial No. 32,454.

therefrom. However, although such cleansing operations are only partially successful, they leave the viscose filaments weak, brittle and inelastic as compared with natural silk. Microscopic examination of such ordinary viscose silk filaments discloses that their inherent weakness as compared with natural silk filaments is due to the fact that whereas, a natural silk filament is of substantially uniform homogeneous solid structure with a smoothly continuous surface; an ordinary viscose filament is of porous structure with The formation of such pores and pits is incident to the primary inclusion and occlusion of sulphur-derivative in the cellulose hydrate and subsequent partial elimination of the same, leaving the cellulose hydrate of spongy texture.

Therefore, an object and effect of my invention'is to provide a method and means for commercially producing viscose silk filaments without occluding free sulphuror its derivatives therein and to thus strengthen the coagulated cellulose hydrate filament by the elimination of pores and pits as aforesaid, and it is the attainment of that result which permits the formation offilaments, in accordance with this invention, as fine as natural silk filaments.

I have discovered that the desirable results aforesaid are attainable by subjecting viscose to the action of P0 ions. Such ions have a beneficial effect if added to or formed in the viscose, or in any bath in which viscose may be coagulated, or in a fluid distinct from either the viscose or the coagulating medium and, in the latter case, may be either alone or in association with other matter affecting the viscose complex. For instance the impure cellulose hydrate product 0 I coagulation of viscose may be subjected to PO ions in a fluid containing dyeing mate-" rial or detergent material.

PO ions have the apparent efi'ect of preventing the formation of sulphur or its de- 1 0' rivatives in insoluble form, and thus render the coagulated products practically self-.

tion a) which the viscose is to be subjected.

' However, in the form of. my invention-herein contemplated, I prefer to subject the viscose to the action of P0 ions in a bath in which'they are derived from an aqueous solution of tri-sodium phosphate :(Na PO although there may be no tri-sodium phosphate present as such in said bath when the viscose is subjected to the action of P0 ions therein.

Although an aqueous solution of either mono-sodlum phosphate or di-sodium phosphate, or said tri-sodium phosphate, alone, will effect coagulation of viscose projected therein particularly if the viscose is of low alkalinity and such solution be hot; I prefer to subject the viscose filament to a preliminary coagulating medium, and such medium may be merely heated atmospheric air.

herefore my improved process herein claimed may be effected by projecting viscose directly into a heated atmosphere through a spmneret orifice or orifices of such diameter t iat when subsequently treated and dried the filaments are of the desired degree of fineness; for instance orifices having a diameter of .025 millimeter. Said filaments are thereafter directed from said heated atmosphere into an aqueous solution containing three percent of tri-sodium phosphate (Na POJ. Such treatment coagulates the viscose to an impure cellulose hydrate complex sufiiciently coherent to be mechanically drawn through and from such bath over a roller.

Filaments thus coagulated in accordance with my invention may require no subsequent treatment other than rinsing with water, as they are practically self-cleansing, in suchcoagulating bath, and-emerge therefrom of substantially uniform homogeneous structure. and with smooth surfaces. When such filaments are dried, preferably under tension, they have unusually high luster,

strength and elasticity, and filaments even finer than natural silk may be thus produced. I

Therefore, I do. not desire to limit; myself to the precise details of structure, arrange-7 ment orprocedure herein set forth, as it is obvious -t at various modificatlons may be made therein without departing from the essential features of my invention, as defined in the appended claims.

However, specific clalms for the process of subjecting precipitated viscose to the action of tri- 1um phosphate and for a process in which viscose is precipitated by any suitable acid before bein subjected to the action of tri-sodium phos ate, are included in Letters Patent of the nited States 1,576,529 granted to me March 16, 1926 pursuant to appli cationSerial'No. 26,825 filed April 29, 1925 and copending herewith.

I 018.1111! 1. The method of manufacturing artificial silk filaments from viscose which consists in coagulating viscose by projecting a fine'filament thereof into a coagulating medium and thence into "an aqueous solution containing PO ions.

2. The method ofmanufacturing artificial silk filaments from viscose which consists in coagulating viscose by projecting a fine filament thereof into a coagulating medium and thence into an aqueous solution containing PO, ions associated with other ions capable of affecting such coagulation.

3. The method of manufacturing artificlal silk filaments from viscose which consists in coagulating viscose by projecting a fine filament thereof into a coagulating medium and thence into an aqueous solution containing PO ions resultant from inclusion of tri-sodium phosphate (Na PO,) in such solution.

4. The method of manufacturin artificial silk filaments from viscose whic consists in coagulating viscose by projecting a fine filament thereof into a coagulating medium and thence into an aqueous solution containing' PO ions, resultant from inclusion of tri-sodium phosphate (Na PQQ in such solution, with another solute capable of affecting such coagulation.

5. The method of manufacturing artificial silk from viscose which consists in projecting a filament of the latter into a heated at- WILLIAM MENDEL.

in which tri-sodium ,phosphate 

